1. Field of the Invention
This invention relates to apparatus and methods for deforming a workpiece so as to produce multiple elongated products simultaneously and, more particularly, to apparatus and methods for forming multiple products simultaneously from a single workpiece on an outer surface of which a lubricant or other fluent coating material is carried.
2. Description of the Prior Art
In the art of forming elongated products, it is known to utilize hydrostatic extrusion techniques, wherein hydrostatic pressure is applied to a billet within a chamber such that the material of the billet is rendered more ductile as the billet is forced through an aperture in a die located at one end of the chamber. Some examples of such techniques may be found in my U.S. Pat. No. 3,740,985, an application for the reissue of which has been filed on Jan. 4, 1974 under Ser. No. 430,984, and has issued as U.S. Pat. RE No. 28,795 on May 4, 1976, and in my copending application, Ser. No. 612,875, filed Sept. 12, 1975, which has issued as U.S. Pat. No. 3,985,011 on Oct. 12, 1976.
It is also known in such art to provide apparatus which includes a die having a plurality of apertures extending therethrough, and to force a workpiece through such die, e.g., by the hydrostatic extrusion techniques disclosed in my patent and my applications mentioned above, so as to produce simultaneously a plurality of elongated products. For example, one such die is disclosed in U.S. Pat. No. 3,901,065 to G. L. Schmehl.
In each of the previously discussed patents and applications, it is taught that a shear transmitting fluid for advancing the billet toward and against the die may advantageously be utilized also as a lubricating material for facilitating the passage of the billet material through the die aperture or apertures. U.S. Pat. No. 3,901,065, in particular, discloses the importance of assuring an even distribution of lubricant among two or more die apertures such that each will be well lubricated, and will produce extruded product at a like rate with the other die apertures. Such patent teaches achieving this desirable result by arraying a relatively small number of die apertures radially equispaced around a circle within a conical mouth of a die at equal distances from an entrance end of the die.
In my copending application, Ser. No. 619,130, filed Oct. 2, 1975, and entitled, "Multiple Aperture Die," which is a continuation of my earlier application of like title, Ser. No. 523,404, filed Nov. 13, 1974, and which has issued as U.S. Pat. No. 3,948,079 on Apr. 6, 1976. I disclose die aperture arrays involving one or more groups of apertures, in each of which groups several apertures, located within a flared mouth area, form a circle surrounding a central aperture at the apex of the flared mouth area. This was considered initially to constitute an arrangement for providing an even distribution of both workpiece material and lubricant to each die aperture. However, it has since been found that, while the workpiece material is in fact apportioned substantially equally among all of the die apertures, the flow of lubricant to each central aperture may be interrupted materially, if more than about three die apertures are present, due to the presence of the surrounding die apertures.
The extrusion of relatively soft and plastic materials through multiholed dies is also known. Such techniques may utilize a number of various die aperture configurations, including linear configurations, as shown in U.S. Pat. No. 2,533,796 to H. Harris and L. M. Ware and, U.S. Pat. No. 3,372,432 to W. R. Howard, and in U.S. Pat. No. 3,564,088 to R. Woodell. Extrusion in accordance with these techniques does not, however, require that a coating of lubricant be employed to facilitate the passage of the billet material through the die apertures. The configurations of apertures in dies for extruding such relatively soft and plastic materials are selected purely for convenience in extruding desired product shapes.
Clearly, it would be desirable to have available alternative arrangements, providing a relatively large number of die apertures useful in producing multiple elongated products simultaneously from a single billet of other than a relatively soft and plastic material, wherein a quantity of lubricating material will be distributed to each of the die apertures, preferably in substantially equal quantities to all of the apertures, such that the operating pressures required in forming the elongated products may be reduced materially.